#EMconf: Knee Dislocation
Knee (tibiofemoral) Dislocation
-MVC is most common mechanism
-Many dislocations self reduce prior to ED presentation so high clinical suspicion is paramount
-If diminished pulse on exam, reduce immediately!
-Popliteal artery injury more common with posterior dislocation (44% of time)
-Check ABI (ankle-brachial index) with all dislocations/suspected dislocations
-ABI < 0.9: needs CT angiogram of leg and vascular surgery consult
-ABI > 0.9: no immediate imaging necessary, monitor for serial vascular exams
-Examine for common peroneal nerve injury (foot drop and sensory deficits on the dorsum of foot). Incidence up to 50%.
-Consult orthopedics, posterior splint/knee immobilizer, observe for serial neurovascular checks and compartment syndrome if no indication for immediate surgical repair
Reference: Arnold C, Fayos Z et. al. Managing Dislocation of the Hip, Knee and Ankle in the Emergency Department. Emergency Medicine Practice. Dec 2017, Vol 19, Number 12.